Monotone versus non‐monotone projective operators

For a class of operators Γ$\Gamma$, let |Γ|$|\Gamma |$ denote the closure ordinal of Γ$\Gamma$‐inductive definitions. We give upper bounds on the values of |Σ2n+11,mon|$|\Sigma ^{1,mon}_{2n+1}|$ and |Π2n+21,mon|$|\Pi ^{1,mon}_{2n+2}|$ under the assumption that all projective sets of reals are determ...

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Veröffentlicht in:The Bulletin of the London Mathematical Society 2024-12, Vol.57 (1), p.256-264
Hauptverfasser: Aguilera, J. P., Welch, P. D.
Format: Artikel
Sprache:eng
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Zusammenfassung:For a class of operators Γ$\Gamma$, let |Γ|$|\Gamma |$ denote the closure ordinal of Γ$\Gamma$‐inductive definitions. We give upper bounds on the values of |Σ2n+11,mon|$|\Sigma ^{1,mon}_{2n+1}|$ and |Π2n+21,mon|$|\Pi ^{1,mon}_{2n+2}|$ under the assumption that all projective sets of reals are determined, significantly improving the known results. In particular, the bounds show that |Πn1,mon|
ISSN:0024-6093
1469-2120
DOI:10.1112/blms.13194